Staph bacteremia: a riddle, wrapped in a mystery, inside an enigma.

Whew! It’s been awhile! Back to it today, with a personal favorite topic- infectious disease.

This study, in particular, is a reminder that medicine is an incredibly humbling career.

All patients with staph aureus bacteremia at Radboud University Medical Center in the Netherlands between January 2013 and April 2016 were retrospectively examined, with primary outcome being newly diagnosed metastatic infection by 18F‐FDG‐PET/CT (here on out referred to as FDG-PET). Subsequent treatment modifications and mortality outcomes were also examined.

There were 148 high-risk staph aureus bacteremic patients, of which 99 underwent FDG-PET. “High risk” characteristics are associated with metastatic infection, and those characteristics are: community acquisition, signs of infection >48 hours before initiation of antibiotics, fever after 72 hours of appropriate antibiotic therapy, positive blood cultures more than 48 hours after initiation of appropriate antibiotics, or already confirmed metastatic foci at the time of presentation.

Of these 99 staph aureus bacteremic patients that underwent FDG-PET, 73.7% had metastatic focus (73 of 99); 71.2% of these patients with metastatic disease had no sign or symptom of this new focus of disease(52 of 73); and of all 73 patients with metastatic infection, 47 patients (64.4%) were diagnosed with metastatic foci in more than one organ system.

That is, 47% of all high-risk staph bacteremic patients have at least 2 organ systems infected (47/99), many of whom had no signs or symptoms. Wow.

Well, ok, but does this really matter? Maybe we just extend their antibiotics longer?

That is just partially correct. Antibiotics were prolonged 15% of the time, 10% of the time a second antibiotic was added on. 25% of time treatment duration was shortened due to no metastatic focus seen. But…. Some form of pus drainage occurred 19% of the time (ie, 19% of all patients who underwent an FDG-PET had an otherwise unplanned drainage).

Some other pearls:

So while I typically focus on EM articles, why do I bring up this paper? It’s not terribly uncommon for us to have the “sepsis bounceback.” The previously critically ill who now re-presents with fever. We’re getting a second chance to find the other foci of infection – and frankly, these are not easy diagnoses to make. Lastly, this paper is a good serving of humble pie- with 71% of patients with a metastatic focus of infection for which they had no sign or symptom.